Re: redundancy via DNS
Hi,
I don't quite understand one bit of your statement...
> This way if one of the connections go down, that DNS server becomes
available
> and those IPs stop being handed out ... effectively removing those IPs
from
> your DNS rotation and automatically failing over to the remaining
> connections. This also provides a load balancing effect.
I can understand how DNS rotation provides rudimentary load balancing, but
how does it "fail over"? The downed DNS server's IPs (because the ISP's
link has servered to it) cannot be transferred over to the other links.
Fail over would mean that somehow the dead DNS server's job is taken over.
To do that with your configuration, you'd need to change the domain name's
DNS entries to either remove the dead DNS server, or to change it's IP. If
people do a DNS lookup, and you have 4 connections, then there is a 1 in 4
chance the DNS lookup may fail. Not all clients will try all the other DNS
servers before declaring the domain name unresolvable.
I'm not picking holes in the system, I'm also trying to come up with a
good solution for this. The solutions we use now are similar (main
difference is we have the servers physically located in different places,
and use some dedicated hardware solutions) so if there was some way to
overcome the above problems, that would be great.
Maybe someone else on the list has already found a way to solve them?
Sincerely,
Jason
----- Original Message -----
From: "Fraser Campbell" <fraser@starnix.com>
To: <debian-isp@lists.debian.org>
Sent: Tuesday, June 19, 2001 10:29 PM
Subject: Re: redundancy via DNS
> ":yegon" <yegon@yegon.sk> writes:
>
> > we have several servers colocated with several ISP's
> > i am trying to sort out some configuration that would ensure good
uptime for
> > customers
>
> We're helping a customer with a similar situation. They have multiple
> incoming Internet connections. What we plan to do:
>
> - Have a DNS server for each Internet connection
> - Servers are replicated/available via every connection
> - Each DNS server gives out IPs only within it's subnet
>
> This way if one of the connections go down, that DNS server becomes
available
> and those IPs stop being handed out ... effectively removing those IPs
from
> your DNS rotation and automatically failing over to the remaining
> connections. This also provides a load balancing effect.
>
> Fraser
>
>
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